On Mon, 25 Jul 2022 05:36:17 -0500, Kai Huang <kai.huang@xxxxxxxxx> wrote:
On Fri, 2022-07-22 at 08:21 -0700, Dave Hansen wrote:
On 7/22/22 06:26, Kai Huang wrote:
> Did a quick look at the spec. It appears ENCLU[EDECCSSA] should be
used
> together with AEX-notify. So besides advertising the new
> SGX_ATTR_ASYNC_EXIT_NOTIFY bit to the KVM guest, I think we should
also
> advertise the ENCLU[EDECCSSA] support in guest's CPUID, like below
(untested)?
Sounds like a great follow-on patch! It doesn't seem truly functionally
required from the spec:
> EDECCSSA is a new Intel SGX user leaf function
> (ENCLU[EDECCSSA]) that can facilitate AEX notification handling...
If that's wrong or imprecise, I'd love to hear more about it and also
about how the spec will be updated.
They are enumerated separately, but looks in practice the notify handler
will
use it to switch back to the correct/targeted CSSA to continue to run
normally
after handling the exit notify. This is my understanding of the
"facilitate"
mean in the spec.
Btw, in real hardware I think the two should come together, meaning no
real
hardware will only support one.
Haitao, could you give us more information?
You are right. They are enumerated separately and HW should come with both
or neither.
My understanding it is also possible for enclaves choose not to receive
AEX notify
but still use EDECCSSA.
Thanks
Haitao
